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CHAPTER 8
WRITE:
REGISTER
=
LEVEL I/O MAPS
X
X
X
X
X
X
X
X
8.1
INTRODUCTORY INFORMATION
The AX-16 is programmable at the register level using I/O (Input/Output) instructions. In BASIC,
the 1 / 0 instructions are INP
(X)
and
OUT
X,
Y
.
In Assembly and most other high-level
languages, the 1 / 0 instructions are similar; for example, the Assembly Language equivalents are IN
AL,DX and OUT DX,AL
.
As
an aid to register-level programming, this chapter describes each ADC-16 register in terms of
function, address, bit structure, and bit functions. The chapter does not go into any programming
detail since it is likely to vary too greatly from person to person.
8.2 I/O REGISTER ADDRESS MAP
The AX-16 uses four consecutive Base Addresses in the computer I/O space, as shown in the
following table. Note that in the table R
=
read, and W
=
write.
LOCATION
FUNCTION
TYPE
Base Address
+O
Base
Address
+
1
Base Address
+2
Base Address +3
Status Register
A/D
Data High Byte
Start
m
A/D
Data Low Byte
Mux & Gain Register
Control Register
R
W
R
R/W*
W
R*
*
Cleared at power-up.
8.3 AID REGISTERS (BASE ADDRESS +O & +I)
While writing to Base Address
+O
initiates an A/D conversion, neither Base Address
+O
nor Base
Address +1 will accept data. Both registers are read-only. However, writing to Base Address
+O
initiates an A/D conversion. Data format of the two A/D Data Byte Registers at Base Address
+1
and
+2 is as follows:
Base Address +O
BIT:
D7
D6
D5
D4
D3
D2
D1
D O
A
write does not register, but
it
initiates an
A/D
conversion.
8 - 1
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